1. Field of the Invention
The present invention relates to an endoscopic apparatus that automatically performs white balance processing and a control method for an endoscopic apparatus.
2. Description of the Related Art
Conventionally, in an electronic endoscopic apparatus, white balance processing is performed for adjusting a variation in color reproducibility due to a variation in sensitivity of a solid image pickup device or a spectral variation of observation light outputted from a light source device.
Conventional white balance processing performs white balance adjustment by adjusting R and B gain values such that image signals of red (R), green (G) and blue (B) read out from an image pickup device that has picked up an image of a white subject can have a ratio of 1:1:1. The white balance values (R and B gain values) defined by the white balance adjustment are recorded in a processor and are used when an electronic endoscopic apparatus is used thereafter.
In other words, when a video scope is connected to an electronic endoscopic apparatus, the electronic endoscopic apparatus loads and defines white balance values corresponding to the video scope. Then, gain control based on the white balance values is performed on the image signals loaded from the image pickup device.
For example, Japanese Unexamined Patent Application Publication No. 2005-131363 discloses an endoscopic apparatus including a scope 210, a light source 220 and a processor 240, as shown in FIG. 18. The scope 210 has a CCD 211 at the distal end of an insertion section thereof. The CCD 211 is a solid image pickup device. The light source 220 supplies illumination light from a lamp 221 to the scope 210 through a light guide 212. The processor 240 performs signal processing on image pickup signals picked up by the CCD 211 by an image processing section 241 and causes an endoscopic image thereof to be displayed on a monitor 230.
In Japanese Unexamined Patent Application Publication No. 2005-131363, a scope memory 214 provided in the scope 210 stores scope data (such as insertion diameter and specifications of the CCD) of the scope and a scope ID, which is identification information for identifying the scope, and white balance data associated by a light source ID of the light source 220, which has been connected thereto in the past, as shown in FIG. 19.
A processor memory 243 including a backup RAM or the like in the processor 240 stores setting data relating to processing in the processor 240 and white balance data associated by the scope ID of the scope 210 and the like, which has been connected in the past, as shown in FIG. 20.
The endoscopic apparatus having such a configuration as disclosed in Japanese Unexamined Patent Application Publication No. 2005-131363 performs auto white balance processing as shown in FIG. 21. In other words, the processor 240, scope 210 and light source 220 are connected. Upon powering on these devices, the processor CPU 242 within the processor 240 in step S101 starts communication with the scope CPU 213 within the scope 210, as shown in FIG. 21.
Then, the processor CPU 242 in step S102 obtains the scope ID from the scope memory 214 through the scope CPU 213 and obtains the light source ID, which is identification information for identifying a light source, from a light source memory 222 within the light source 210.
Next, the processor 242 in step S103 searches white balance data corresponding to the light source ID from the scope memory 214 through the scope CPU 213 based on the light source ID.
Then, the processor CPU 242 in step S104 determines whether corresponding white balance data exists within the scope memory 214 or not based on the search result information from the scope CPU 213.
If it is determined that corresponding white balance data exists within the scope memory 214, the processor CPU 242 in step S107 loads the corresponding white balance data from the scope memory 214 through the scope CPU 213.
On the other hand, if it is determined that no corresponding white balance data exists within the scope memory 214, the processor CPU 242 in step S105 searches white balance data corresponding to the scope ID from the processor memory 243 based on the scope ID.
Then, the processor CPU 242 in step S106 determines whether corresponding white balance data exists within the processor memory 243 or not.
If it is determined that corresponding white balance data exists within the processor memory 243, the processor CPU 242 in step S107 loads the corresponding white balance data from the processor memory 243. If it is determined that no corresponding white balance data exists within the processor memory 243, the processor CPU 242 exits the processing.
Then, the processor CPU 242 in step S108 performs white balance calculation processing by using the loaded corresponding white balance data and exits the processing.
In Japanese Unexamined Patent Application Publication No. 2005-131363, if no corresponding white balance data exists within the scope memory 214 and processor memory 243, processing ends.
On the other hand, an apparatus in Japanese Unexamined Patent Application No. 2003-265410 displays an error message if no corresponding white balance data exists and prompts a user to perform manual white balance processing. Then, the manual white balance processing is performed in response to the press of a W/B switch 244 (refer to FIG. 18) by a user based on the error message. After the manual white balance processing is performed, the white balance data associated with a light source ID and a scope ID is stored within the scope memory 214 and processor memory 243.
As described above, if corresponding white balance data exists within the scope memory 214, an optimum white balance in accordance with characteristics of a scope and light source used therewith can be obtained. If no corresponding white balance data exists within the scope memory 214 and corresponding white balance data exists within the processor memory 243, an optimum white balance in accordance with the characteristic of the scope can be obtained at least.